Dark states and delocalization

Competing effects of quantum coherence on the efficiency of light harvesting systems

Zixuan Hu, Gregory S. Engel, Fahhad Alharbi, Sabre Kais

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Natural light harvesting systems exploit electronic coupling of identical chromophores to generate efficient and robust excitation transfer and conversion. Dark states created by strong coupling between chromophores in the antenna structure can significantly reduce radiative recombination and enhance energy conversion efficiency. Increasing the number of the chromophores increases the number of dark states and the associated enhanced energy conversion efficiency yet also delocalizes excitations away from the trapping center and reduces the energy conversion rate. Therefore, a competition between dark state protection and delocalization must be considered when designing the optimal size of a light harvesting system. In this study, we explore the two competing mechanisms in a chain-structured antenna and show that dark state protection is the dominant mechanism, with an intriguing dependence on the parity of the number of chromophores. This dependence is linked to the exciton distribution among eigenstates, which is strongly affected by the coupling strength between chromophores and the temperature. Combining these findings, we propose that increasing the coupling strength between the chromophores can significantly increase the power output of the light harvesting system.

Original languageEnglish
Article number064304
JournalJournal of Chemical Physics
Volume148
Issue number6
DOIs
Publication statusPublished - 14 Feb 2018

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Chromophores
chromophores
Energy conversion
energy conversion efficiency
Conversion efficiency
antennas
Antennas
energy conversion
radiative recombination
excitation
parity
eigenvectors
trapping
excitons
output
electronics

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Dark states and delocalization : Competing effects of quantum coherence on the efficiency of light harvesting systems. / Hu, Zixuan; Engel, Gregory S.; Alharbi, Fahhad; Kais, Sabre.

In: Journal of Chemical Physics, Vol. 148, No. 6, 064304, 14.02.2018.

Research output: Contribution to journalArticle

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